Organic light emitting devices/diodes (OLEDs) are often made from electroluminescent polymers and small-molecule structures. These devices have received a great deal of attention as alternatives to conventional light sources in display devices, lighting devices, and other applications. For example, OLEDs in an array may provide an alternative to liquid crystal (LC) based displays, because the LC materials and structures tend to be more complicated in form and implementation.
One of the many benefits of OLED-based displays is that they do not require a light source (backlight) as needed in LC displays. To wit, OLEDs are a self-contained light source, and as such are much more compact while remaining visible under a wider range of conditions. Moreover, unlike many LC displays, which rely on a fixed cell gap, OLED-based displays can be flexible.
While OLEDs provide a light source for display and other applications with at least the benefits referenced above, there are certain considerations and limitations that can reduce their practical implementation. To wit, OLED materials are susceptible to environmental degradation. For example, exposure of an OLED display to water vapor, or oxygen, or both can be deleterious to the organic material and the electrical components of the OLED structure. As to the former, the exposure to water vapor and oxygen can reduce the light emitting capability of the organic electroluminescent material itself. As to the latter, for example, exposure to these contaminants of reactive metal cathodes commonly used in OLED displays over time can result in ‘dark-spot’, areas and reduce the useful life of the OLED device. Accordingly, it is beneficial to protect OLED displays and their constituent components and materials from exposure to environmental contaminants such as water vapor and oxygen.
In order to minimize environmental contamination, OLEDs must be sealed between two layers, which are often glass substrates. Moreover, the sealing process must not expose the OLED material to excessive heat to prevent destruction of the OLED material.
What is needed, therefore, is a method of sealing the glass substrates to form a hermetically sealed OLED structure that overcomes at least the shortcomings described above.
Defined Terminology
As used herein, the term ‘perimetrically’ may mean substantially following the contour of an edge of a surface but being a finite distance from the edge of the surface. The magnitude of the finite distance is application driven. For purposes of illustration, a material disposed perimetrically over a substrate having a rectangular outer edge is rectangular in shape with a finite distance between the material and the outer surface. It is emphasized that the defined terminology is in addition to the ordinary meaning of ‘perimetrically’.